I was under the impression that the Purim mitzvah of matanot l'evyonim, giving gifts to the poor, had to be done directly -- find two or more poor people and give to them. This answer on a related question says:
There are lots of tzedakah funds who collect for poor people that collect from donors outside the country. You might want to find one of those.
Does an indirect gift like this fulfill the mitzvah? If so, do we have to give early enough to ensure that they will distribute the funds in time, or is my giving the gift (in time) sufficient and I can rely on the tzedakah fund to eventually distribute it? Do I need to tell the tzedakah fund that this is for Purim?